The part about not being able to prove things is sort of a non sequitur because the whole idea here is that some things are, for the most part, simply beyond us. Or to put it differently, some things can only be "validated" by personal experience.
Granted that people often abuse that claim to personal experience. And granted that such experiences probably don't validate particular dogmatic beliefs. I'm only invoking this for the general proposition that a metaphysical plane can't be dismissed out of hand and that some people might be more capable of experiencing that aspect of reality better than others.
Also, in terms of never being able to prove claims, that's debatable. If you're talking peer reviewed studies, then in general you're probably correct. But again, we might be talking about something that doesn't abide systematic study - at least not in the ways we're able to understand.
But there are plenty of well documented anecdotal data. There is even some that probably can stand up to such scrutiny. For example there are Tibetan monks who have been documented being able to raise their body temperature through meditation. And they do it to such an extent that they can dry a blanket soaked with water in a room that is below freezing. At the very least this takes you into some very curious mind-body territory.
If they are beyond us, then they can't be validated, even anecdotally. At best a person could sense something, but if it's beyond us it would not be sensical.
People add things to their experience all the time. Near Death Experiences are a good experience of this. Some Christians report seeing Jesus or some Christian figure. Hindus report seeing Krishna or some Hindu figure. Muslims report seeing Mohamed or some Muslim figure.
Even people who witness something as mundane as an Auto accident give accounts of it that are embellished and even change over time. "Experience" is one of the least reliable ways of Knowing.
Ah ya, sure they have. I'm sure Cletus's well documented anecdotal Alien Abduction story is 100% legit too.
With all that said, it's funny we are even discussing these issues in such a vague mystical fashion. The Authors of Holy books seem far more certain about this "beyond us" plane of reality. With amazing(even by today's standards) and grandiose displays of might and ability from their gods and other beings. With all sorts of witnesses to boot. Not only that, but receiving very explicit instructions and information(much of it disproved by Science btw). Why such a contrast?
The contrast exists because the Ancients were very much like us, they were very Curious and wanted to Know things. However, they lacked the foundational Knowledge that we now possess. In their lust for Knowledge, they often used their Imaginations to fill that gap, much the same way we use ours today for Entertainment. Hence was born gods and places beyond our perception.
Unfortunately, "Spiritual" people, despite honestly and earnestly seeking Truth and other noble things are not actually experiencing some Phenomena of Reality. Instead what they are experiencing is the phenomena of mimicry of the Ancient Mind. It is full of Wonder and Amazement, I experienced it myself, by being a Child and then later as a Spirit Filled Born Again Pentecostal Christian. Both times it was due to looking at Reality from a state of Ignorance. As a Child it was not my choice, as a Christian I chose to be Ignorant in order to experience it.